1. the subject of theoretical grammar its relations to other branches of linguistics

31. The category of voice
The form of the verb may show whether the agent expressed by the subject is the doer of the action or the recipient of the action (John broke the vase - the vase was broken). The objective relations between the action and the subject or object of the action find their expression in language as the grammatical category of voice. Therefore, the category of voice reflects the objective relations between the action itself and the subject or object of the action:
The category of voice is realized through the opposition Active voice::Passive voice. The passive is marked both in meaning and in form and the active as unmarked both in meaning and in form.
The realization of the voice category is restricted because of the implicit grammatical meaning of transitivity/intransitivity. In accordance with this meaning, all English verbs should fall into transitive and intransitive. However, the classification turns out to be more complex and comprises 6 groups:

1. 
   Verbs used only transitively: to mark, to raise;
   
2. 
   Verbs with the main transitive meaning: to see, to make, to build;
   
3. 
   Verbs of intransitive meaning and secondary transitive meaning. A lot of intransitive verbs may develop a secondary transitive meaning: They laughed me into agreement; He danced the girl out of the room;
   
4. 
   Verbs of a double nature, neither of the meanings are the leading one, the verbs can be used both transitively and intransitively: to drive home - to drive a car;
   
5. 
   Verbs that are never used in the Passive Voice: to seem, to become;
   
6. 
   Verbs that realize their passive meaning only in special contexts: to live, to sleep, to sit, to walk, to jump.
   

Three types of passive constructions can be differentiated: 1) direct primary passive; 2) indirect secondary passive; 3) prepositional tertiary passive.
Some English verbs can admit only one object - the direct one: e.g. Mary saw him.
When such an object becomes the subject of a passive construction, the latter is called direct primary passive: e.g. He was seen by Mary.
There are many verbs in English that take two objects in the active construction (direct and indirect): e.g. I gave him a book. She told the story to her sister.
These verbs admit of two passive constructions:

1. 
   A book was given to him. The story was told to her sister. (the direct primary passive)
   
2. 
   He was given a book. Her sister was told the story. (the indirect secondary passive)
   

The indirect (secondary) passive is not infrequent in verb-phrases with the verb to give, such as: to give credit, to give command, to give a chance, to give a choice, to give an explanation, to give an opportunity, to give orders, to give shelter, and the like.
e.g. He was given a good to chance to argue.
She is given an opportunity to go to the south in summer.
Suppose, you are given a choice. What would you prefer?
However, many verbs in English may take a direct and an indirect object in the active construction but admit only one passive construction — the direct passive, e.g.: to bring, to do, to play, to telegraph and many others. The list could be extended.
Next come constructions with the so-called prepositional or tertiary passive. The subject of the passive construction corresponds to the prepositional object of the active construction. This “detached” preposition retains its place after the verb.
e.g. Everything was taken care of.
She could not bear being read to any longer.
He was constantly being laughed at.
It should be noted that some scholars admit the existence of Middle, Reflexive and Reciprocal voices.
"Middle Voice" - the verbs primarily transitive may develop an intransitive middle meaning: That adds a lot; The door opened; The book sells easily; The dress washes well.
"Reflexive Voice": He dressed; He washed - the subject is both the agent and the recipient of the action at the same time. It is always possible to use a reflexive pronoun in this case: He washed himself.
"Reciprocal voice”: They met; They kissed - it is always possible to use a reciprocal pronoun here: They kissed each other.
We cannot, however, speak of different voices, because all these meanings are not expressed morphologically.